1. Field of the Invention
The present invention relates to a system for displaying a segment by electromagnets, of the type employed in an automatic and remote-controlled digital display.
2. Description of the Prior Art
Many systems for display by electromagnetic segments are already known. Among these can be mentioned in particular the system comprising two electromagnets in the form of ferrite disks housed within an insulating support, two permanent magnets mounted in series but parallel to each other on each side of a pivot-pin, and a control circuit for energizing the electromagnets in order to produce a magnetic field. As a function of judiciously chosen polarities of the magnets employed, the magnetic field permits rotation of the permanent magnets about the pivot-pin through an angle such that the segment which is rigidly fixed to said pivot-pin can move from a visible active position to a hidden active position. When the segment is brought into one of said positions, its return displacement to the other initial position is obtained by reversing the polarity of the pulses delivered by the control circuit so as to reverse the polarities of the permanent magnets. The assembly is so designed that a magnetic remanence within the electromagnets is necessary in order to maintain the permanent magnets against the electromagnets unless the control circuit is continuously maintained in the energized state, which is not a desirable method for ensuring good reliability, particularly as seven segments and therefore the same number of systems are employed for displaying a digit.
Furthermore, in a system of this type, there are no means of checking whether the segment is actually in one of the two active positions mentioned above. Should the segment occupy an indeterminate position for any reason, it is not easy in such a case for the user to know whether the segment is hidden or whether an incident has occurred.